1. Field of the Invention
The present invention relates to boat propelling systems, and more specifically, to a boat propelling system including an electric motor arranged to pivot a propelling system main body in a right-left direction with respect to a hull.
2. Description of the Related Art
As disclosed in JP-A 2006-199189, for example, use of an electric motor to pivot an outboard engine (propelling system main body) in a right-left direction with respect to a hull for steering the hull is a conventional technique.
According to the technique in JP-A 2006-199189, a target pivot angle of a propelling system main body (e.g., outboard engine main body) which pivots with respect to the hull, is set by using a steering wheel turning angle or the like. Then, based on an angle difference between the target pivot angle and an actual pivot angle of the outboard engine, an amount of control of the electric motor is determined. The electric motor is driven in accordance with the determined amount of control and thus the outboard engine is pivoted in the right-left direction with respect to the hull.
However, if there is an abnormality such as deterioration of the electric motor, there can be cases where it is impossible to vary the actual pivot angle appropriately. Then, there will be an unacceptably large gap between the actual pivot angle and the target pivot angle. In other words, abnormalities regarding the steering on the propelling system main body can cause an unacceptably large gap between the user's operation and an actual behavioral change of the boat. JP-A 2006-199189 makes no consideration on this point, and therefore makes no disclosure, nor indication, regarding abnormality determination on the steering of outboard engine.